Recent forecast updates from multiple meteorological models indicate an incoming weather system with northerly winds and widespread rain expected to arrive over Istanbul on September 22, driving cooler overnight temperatures and creating the near-even split in market-implied odds between a low of 10°C or below versus 20°C or higher. Ensemble guidance shows minimum temperatures clustered around 13–15°C under cloudy, wet conditions, consistent with September climatology where passing fronts can produce 3–5°C drops below seasonal averages of roughly 18°C. Key variables differentiating outcomes include the precise timing of the frontal passage, total rainfall amounts that enhance evaporative cooling, and local wind patterns that may prevent full mixing of cooler air near the surface. Updated model runs and official briefings from agencies like the Turkish State Meteorological Service in the next 48 hours will likely resolve much of the current uncertainty ahead of market resolution.